There is a well-known diaphragm valve that includes a body provided with a fluid inflow passage, a fluid outflow passage, and a concave portion opened upward, an annular seat disposed on the bottom of the concave portion of the body, and an elastically deformable diaphragm which opens and closes a fluid passage by being pressed against or separated from the seat.
When the diaphragm of the diaphragm valve is broken, fluid in the valve may leak externally. When toxic gas or corrosive gas is used as the fluid, the leakage poses a risk.
Generally, the durability count of the diaphragm is checked in advance, the count until breakage is set in consideration of variations, and the diaphragm is replaced when this count is reached to prevent the diaphragm from being broken. However, the diaphragm may be broken before this count is reached.
Accordingly, PTL 1 discloses the provision of a sensor for monitoring the wear state of a diaphragm.